Portable computers often include structure for reducing their power consumption in order to increase the length of time they can run based on battery power, their so-called run time. Power consumption in such a portable computer can be reduced by terminating the supply of power to various devices in the portable computer. This can include turning off the display, stopping the hard drive, and other such features. Current systems of this type have used a time-out period in a register on the computer, e.g. a register in the basic input output system (xe2x80x9cBIOSxe2x80x9d). Each time the user takes an action on the keyboard or mouse, the BIOS counter is reset. After a user-selectable, predetermined period of inactivity, the power down mode is entered. The time before auto power down usually ranges between 30 seconds and 30 minutes.
Users often find it annoying if the screen blanks while they are taking an action such as reading the contents of the screen. Users hence often choose longer time outs to avoid this situation. However, this increases power consumption, and hence significantly decreases the battery operation time.
The present application teaches a system which recognizes that the user""s passive activity, like reading, should be taken into account when determining the time-out for such a system. According to the present invention, user activity is monitored in real time by a detection device, e.g., a camera, which monitors for the presence of a user in real time. The user""s presence causes the computer to remain in the xe2x80x9conxe2x80x9d or fully powered state. When the user is not present, the computer reverts to its low power state.
According to an aspect of the invention, a computer monitors the presence of a user, enters a power increase state when the user is present, and a power decrease state when the user is not present.
A power control device for a computer has a power control module which reduces power consumption of the computer in a specified mode; and a user detection system, which detects the presence of a user, and operates the power control module based on the presence of the user.